The Red Devils snapped up Jadon Sancho for £72.9m from Borussia Dortmund, and have reportedly agreed a £41m deal to sign Raphael Varane from Real Madrid. And Klopp admitted he is puzzled over how United secured the deals from a financial perspective.
"We all know the situation of Chelsea and City and PSG," Klopp said ahead of Liverpool's opening match against Norwich. "What United are doing, I don't know how they did it. We have our own way to do it. We are allowed to spend the money we earn, that we always did.
"This year we spent before we earned money with Konate because after last season, just to be clear, we cannot take any risk in this position at all. I'm never surprised about the financial power of Chelsea, City or United, I've been here long enough to know they always find a solution to these things. We cannot compare to the other clubs. They obviously don't have any limits. We have limits."
Ibrahima Konate has been Liverpool's only transfer of the summer until now, but the Red have been linked to Atletico Madrid's Saul Niguez.
Virgil van Dijk returned to the first team after a lengthy spell on the sidelines and signed a new four-year contract on Friday. Klopp expressed his delight at tying the Dutch defender down to fresh terms - joking it was a good thing that the Reds didn't have to buy Van Dijk in the current market.
"It's great news. We are really happy that he is happy here. It's absolutely great news. Imagine if we had to buy this boy now! Thankfully we only have to give him a new contract," Klopp said.
Van Dijk said: "It is something to be very proud of, that I am very proud of, that my wife and my kids are very proud of and obviously my agency. All the hard work we’ve put in so far continues and I am looking forward to what the future brings together with Liverpool. I’m delighted, very happy and proud.”